Means for concentrating minerals



Dec. 28, 1937.

E. S. CURTIS MEANS FOR CONCENTRATING MINERALS Filed Jan. 7, 1955' 2 Sheets-Sheet 1 Mum/5m BY 2 a A'ITORN 3 ll Z4 Z5 F 1 25 F INVENTOR.

Dec. 28, 1937. E. s. CURTIS MEANS FOR CONCENTRATING MINERALS Filed Jan. 7, 1935 2 Sheets-Sheet 2 11 JENTOR. M1. @1434 BY ilfiewg m mm Patented '28, 1937 UNITE-D .shufn'as PATENT. OFFICE I I 2.403.843 I I "Ziiififififif Application January '1, 1935, Serial No. 621 4 Claims. (cl. zoo-430 My l vention broadly contemplates the provision of a process for recovering valuable minerals from ore which consists in running a mixture of pulverized ore and water; in a shallow stream a downwardly in an inclined travelling and water tight sluice overlaid with longitudinaland transverse bars arranged endwise and preferably lunged together to form amatting with longitudinal and transverse series of pockets adapted to impede-the flow of the stream and to cause local. countercurrents in the pockets fortrapping and confining the mineral constituents in the relatively small pockets of shallow depth while the lighter and valueless constituents are constantly agitated and kept in suspension by reason of countercurrents, or-eddies which are set up by the impingement of thepulp stream on the transverse bars, and controlling the flow of the stream.

Contrary to the action of a stream of substantial depth as used in ordinary sluices in which transverse riilles are provided on the bed and the direction of flow is constantly in one direction, due to the hydrostatic pressure which prevents countercurrents, I provide a streamof a depth substantially corresponding to thedepth of the pockets, so that there can be no pressure to resist the formation of countercurrents locally in each of the pockets as the pulp stream moves from the upper to the lower end ofthesluice. Thus, the 30 tendency of the eddies is to wash the heavier elements of the pulp backwardly in the pockets to positions adjacent the rear margins thereof while the water and lighter elements are gradually moved downwardly in the sluice and ultimately a disposed of as in other concentrators. The sluice may be either stationary or movable, but if movable the direction of movement is always opposite to the direction of flow of the pulp stream. The rate offlow and inclination of the bed is variable to meet different conditions. Preferably, the matting forming the pockets of the bed is formed of thin metal strips usually of a width not exceeding one half inch and the pockets formed by the bars are therefore shallow and of one square inch, or slightly more in area, thereby preventing displacement and agitation of the trapped minerals therein.

I have discovered that the bed of the sluice may be satisfactorily formed of a heavy napped material, similar to carpeting, with the napped side uppermost so that the lower edges of the longitudinal and transverse bars of the matting will nest in the nap of the bed and form seals at the botton edges of the bars to prevent loss of the trapped materials from the pockets. Thus,

much of the finely divided mineral constituents of the ore will be retained in the nap of the fabric bed which wouldotherwise be washed outwith the valueless constituents. Clean-ups may be made at frequent intervals when the bed is stationary or 5 continuously when the bed is movable.

The apparatus necessary to carry out the above described process is simple, efllcient and durable and differs but slightly fromstandard forms of. sluices. Said apparatus, as shown in the acl0 companying drawings, is subject to modification, within the scope of the appended claims without departing from the spirit of my invention. In said I drawings:

' Fig. 1 is a side elevation of a concentrator embodying my invention and arranged with a movable sluice;

Fig. 2 is an enlarged transverse sectional elevation of the same on line 2- 2 of Fig. 1;

Fig. 3 is a transverse section of the same online 33 ofFig.1;.

. Fig. 4 is a fragmentary enlarged section, in elevation, of the concentrator, on line 44 of F 2;

Fig. 5 is a fragmentary longitudinal section of the sluice, substantially enlarged, shown. 'associated with a suitable driving means;

Fig.- 6 is a fragmentary plan. view of the sluice; and

Fig. 7 is a section of the sluice on line 1-1? of Fig. 6.

Briefly described, the apparatus in a preferred form may include a frame F on which a movable sluice S is supported at a suitable inclination and includes a bed B, a hopper H for receiving and discharging quantities of pulverized ore onto the bed B, a water pipe W for supplying water in sufflcient volume to the sluice for mixture with the ore, adischargeduct D for receiving and discharging the products of a concentration operation, and a receptacle B. into which the concentrated and collected minerals are fed for amalgamation, or. for removal to other points for amalgamation.- Theframe F is formed with sides i I provided with longitudinally disposed cleats 2, 2 on their inner surfaces at corresponding distances from the upper edges of the sides 'I over which the sluice S is adapted to move, as shown in Fig. 2. The upper surfaces of the cleats 2 are inclined downwardly from the sides I so that the overlying margins of the bed B will be disposed at centrator is in use.

4. It will be noted that the lateral margins of the fabric elements 3 and tare substantially extended outwardly of the matting 5 (see .Fig. '1) so as to yieldably and frictionally engage the cleats 2 and form water tight sides of the sluice.

The matting 5 may be formed of any suitable metal but preferable of bars of flat cross section, comparatively thin and narrow, and hinged together individually or in groups so as to provide sufllcientflexibility topermit the rolling of the'matting into a bundle when removed from the bed B and continuous belt-like movement with the other elements of the bed when the con- 1 have shown a well known form of metal matting which is formed in a plurality of transverse units by alternately bending metal strips in opposite directions so as to provide in each unit a series of oppositely open- U shaped sections which longitudinally overlap and are hinged together at corresponding points.

Thus. each of the U shaped sections of the matting forms a shallow pocket 6 having'transverse portions 1, 1 and longitudinal portions 8, 8 and hinged to the longitudinally adjacent section by means of rods 9, 9 etc., as shown in Fig. 6. The sluice operates as a belt over a pair of driven end rollers l and II mounted on transverse shafts l0 and II, respectively, which are supported on the sides I, a plurality of intermediate rollers l3, l3, etc. held on shafts l4, l4 etc. so that their peripherieswill be in the same inclined plane as the driven rollers Ill and II, as shown in Fig. 4, and additional rollers 15,16 and II, on shafts l8, l9 and 20, respectively.

One of said rollers, as at It in Fig. 4, may be adjustably mounted for tightening the sluice, as by means of an adjustable bearing 2| as shown in Fig. 1, or otherwise. Power may be applied to the end rollers I I) and H and to certain of vthe intermediate rollers II, as shown in Fig. l,

by the provision of a drive shaft 22 externally of and paralleling the sluice S and provided at each point with a worm 23 operatively engaged with a worm gear 24 aflixed to an end of the shaft associated with each of said rollers. Shaft 22 may be operated by any suitable means from a source of power.

As shown in Fig. 3, the end portions of the rollers l0 and II are preferably provided with flanges 25, 25 of inclined cross section to correspond to the inclination of the cleats 2, so as ,to form and retain the sides of the sluice, and other of the rollers associated with said bed may be'similarly flanged if necessary.

When a stationary sluice is employed in lieu of the movable sluice shown and described herein, the matting is positioned upon the fabric material 4 'which may be attached to the canvas backing 3 or applied directly to a wooden or metal floor of the sluice. In either event it is desirable to so attach the fabric 4 and the matting 5 that they may be readily removed and cleaned so as to completely recover the mineral values which may have accumulated in the nap of the material.

. In operation, pulverized ore is continuously fed into and from the hopper H upon the downwardly inclined but upwardly moving portion of the sluice while water from the pipe W is continuously' mixed with the ore. The volume of water is regulated at the point of discharge so that the depth of the stream will be but slightly napped material 4, and-a metal matting 5 is suitably secured to the napped side of the materialabove or substantially corresponding to the level of the upper edges of the bars I and 8 of the metal matting. The rate of flow of the pulp stream, the inclination of the sluice and the rate. at which the sluice moves are vital [actors which affect the operation of the concentrating apparatus. I have determined that the shallower the stream relative to the depth of the pockets 8 of the matting, the more complete will be concentration and recovery of the mineral values of the ore.

The flow of the pulp stream downwardly in the sluice is gradual, from one transverse series of the pockets 6 to the next, and the impingement ofthe fluid on each successive rows of the portions 1 impedes the flow and sets up countercurrents, or eddies, as shown in Fig. 5, which tend to move the particles of mineral backwardly in the pockets against the transverse portions 1 at the back of the pockets, while the lighter elements of the pulp are kept in suspension and move outwardly from the pockets and upwardly into the stream and thence into or over succeeding pockets, until .they finally are discharged into the outlet duct D for ultimate disposition with the residue.

The metal strips of which the pockets 6 are formed are thin and neatly nest in the nap of the material 4 so as to prevent escape of the mineral particles therebeneath, and the pockets are of relatively small area and serve to confine the mineral particles therein against lateral displacement, as is posslble in sluices where transverse riflles are provided without longitudinal partitions.

It is obvious that the continuously or intermittently moving sluice will deposit the loose mineral constituents of the ore in the receptacle R where it may be amalgamated or from which I it may be removed for amalgamation at another point, and any finely divided particles which may adhere to the nap of the bed may be washed or otherwise removed from the bed, either while in position on the frame F or when thesame is removed and cleaned.

The concentrating means and method herein disclosed are particularly adapted for use in the inexpensive treatment of material containing valuable minerals or substances and of large tonnage and, moreover, for treating and concentrating alluvial or placer deposits where the gold or the other metalsare too finely divided to be economically recovered by existing methods.

My apparatus may be designed to handle and treat a varyingquantity of material without loss of efliciency. As an illustration, a concentrator constructed for a maximum capacity of one hundred tons per hour will function at a capacity of one ton per hour with equal eificiency. This characteristic is of great importance as it makes itpossible to handle material direct from the screening plant without intervening storage and attendant feeders.

On the other hand a concentrator of comparatively small capacity or output and minimum cost of construction is enabled to handle and treat a relatively large tonnage of material; in fact a tonnage comparable with a far greater number of standard concentrating tables. Thus, with my apparatus and method I am enabled to effect a substantial economy in labor, housing, machinery and equipment and to economize as well in the amount of space required to erect a complete unit. Other advantages will readily occur to those skilled in the art of mineral concentration;

I have discovered that the pockets 6 should vary to a certain extent in area, depending upon the character and mesh of the material to be treated. Likewise the pitch of the sluice is variable for the same reasons, inorder to obtain the most satisfactory results. Probably, with a material of one-sixteenth mesh, or less, the size of the pockets should not exceed one inch laterally and longitudinally, the pitch of the sluice should in such case be approximately one and one-half inch per foot and the depth of the pulp stream should be approximately one-half an inch, while the depth of the pockets 6 should be approximately three-eighths to one-half of an inch.

A pulp stream of greater depth mentioned above would, by reason of the added hydrostatic pressure, prevent a proper agitation of the lighter elements of the pulp and also prevent the eddies which are depended upon for moving the recovered and trapped particles of minerals backwardly in the pockets, so any resident-lighter elements mixed therewith might be separated and suspended in the water. Thus, the countercurrents set up perform three separate and distinct functions, namely: first, an agitation and sorting of the semi-concentrated material in the pockets; second, the movement of the clean concentrates to the rear portions of the pockets where it finally rests; and third, the merging of the countercurrents with the pulp stream above the pockets carries the lighter particles of dross, into the main pulp stream for discharge and simultaneously maintains constant agitation locally in each of the pockets.

It should be noted that this invention provides with a simple -flat conveyor belt, a travelling water tight sluice of 'which the sides are formed by the upturned edge portion of the belt. This insures the maintaining of the desired amount of water throughout the length of the sluice without loss by leakage at the sides of the sluice as is commonly the case in sluices having separate or fixed sides independent of the, travelling bed. loss of water at certain points in the sluice prevents concentration at such points.

What I claim is:

1. An apparatus for recovering minerals from ore comprising an inclined support, ,a flexible bed carried by said inclined support and having a relatively resilient surface, means holding the side marginal edge portions of said flexible bed in an upturned position to define a relatively shallow water-tight inclined trough substantially U- shaped in cross-section, a riiiie positioned in said inclined trough, said riilie having a plurality of transverse and horizontal. strips of thin crosssection embedded in the resilient surface .of said bed and defining relatively shallow pockets, said strips being embedded in said resilient surface to form a seal and prevent underflow of material between adjacent pockets, said riiiie extending transversely of said bed to the upturned side marginal portions thereof, and means for feeding finely divided ore and water to the upper portion of said inclined bed. r

2. An apparatus for recovering minerals from ore comprising an inclined support, an endless driven flexible bed carried by said inclined support and having a relatively closely napped surfaceysaid bed being supported by rollers adjacent the upper and lower ends thereof, means intermediate said upper and lower rollers for defleeting the "side marginal portions of said bed upwardly to define a relatively shallow .watertight inclined trough substantially U-shaped in cross-section, a riflie positioned in said inclined trough, said riflle having a plurality of transverse and longitudinal strips of thin cross-section embedded in the nap of saidbed and defining relatively shallow pockets, said strips being embedded in the nap of said bed to form a seal and prevent underflow of material between adjacent pockets, said riiiie being movable with said bed in a direction counter to the gravitational flow of material down said bed, and means for feeding finely divided ore and water to the upper portion of said inclined bed.

3. An apparatus for recovering minerals from ore comprising an inclined support, an endless driven flexible bed carried by said inclined support and having a relatively closely napped surface, said bed being supported byrollers adjacent the upper and lower ends thereof, means intermediate said upper and lower rollers for deflectingthe side marginal portions of said bed upwardly to define a relativelyshallow watertight inclined trough substantially U-shaped in cross-section, said rollers each having end flanges cooperating with said means for maintaining said flexible bed in the shape of a relatively shallow trough, a riiiie positioned in said inclined trough, said riiiie having a plurality of transverse and longitudinal strips of thin crosssection embedded in the nap of said bed and defining relatively shallow pockets, said strips being embedded in the nap of said bed to form a sealand prevent underflow of material between adjacent pockets, said rifiie being movable with driving rollers adjacent the upper and lower ends thereof, additional rollers supporting said bed intermediate said driving rollers, means adjacent the sides of said inclined support and intermediate said upper and lower driving rollers for deflecting the side marginal portions of said bed upwardly to define a relatively shallow watertight inclined trough substantially U-shaped .in cross-section, said driving rollers each having end flanges cooperating with said means for maintaining said flexible bed in-the shape of a relatively shallow trough, a riflie positioned in said inclined trough, said riiiie having a plurality of transverse and longitudinal strips of thin crosssection embedded in the nap of said bed and defining relatively shallow pockets, said strips beingembedded in the nap of said bed to form a seal and prevent underflow of material between adjacent pockets, said riiiie being movable with said bed in a direction counter to the gravita- 1 tional flow of material down said bed, and means for feeding finely divided ore and water to the upper portion of said inclined bed to a depth not substantially exceeding the heighth of the strips forming said riifle.

EDWARD S. CURTIS. 

